Device for controlling flow of solids in a powdered solid and gas contacting operation



J. S. PALMER Feb. 13, 1951 2,541,662 DEVICE EoR CONTROLLING FLOW 0EsoLDs 1N A POWDER SOLID AND GAS CONTACTING OPERATION nml Filed Jan. 23,

. Maag/V704g JEM/ELL 5,. PHL/15E AT ORNEY.

Patented Feb. 13, 1951 SOLIDS IN A POWDERED SOLID AND GAS CONTACTINGOPERATION Jewell S. Palmer, Baytown, Tex., assignor, by

mesne assignments, to Standard Oil Development Company, Elizabeth, N.J., a corporation oi Delaware Application January 23, 1948, Serial No.3,904

2 Claims. (Cl. 23-288) The present invention is directed to a device forcontrolling the ow of solids in a catalytic process in which a fluidizedpowder is employed as a catalyst therein.

In the catalytic cracking of hydrocarbons, particularly those processesknown to the art as the fiuidized powder process, a finely divided solidis usually suspended in the petroleum product which is to be cracked. Inthis operation it is customary to suspend in a hydrocarbon in avaporized or partially vaporized condition nely divided particles ofcatalyst which are carried along with the hydrocarbon to a reaction zonewherein conditions oi temperature and pressure are maintained to causecracking of the hydrocarbon. 'I'he catalyst is separated from thehydrocarbon in the reaction chamber, and, since it is coated with-carbonaceous material and carbon, it is necessary 4to remove thecarbonaceous material and carbon before it is suitable for reuse in theprocess. Therefore, it is customary to provide a regeneration zone inwhich combustion conditions are maintained for -burning the carbonaceousmaterial and carbon from the catalyst, leaving the catalyst in acondition suitable for reuse in the process.

The enormous amount of heat generated by burning oil' thefcarbonaceousmaterial from the catalyst is usually sumcient to maintain crackingconditions in the reaction zone. The regenerated catalyst is thencarried back to the reaction zone ior reuse in the process as described.

One great difficulty to the operation of the process in which theiiuidized solid technique is employed is that the catalyst which ows asa fluid is very diicult to handle in the large conduits required in theprocess. For example, this catalyst is handled as a fluid although it isa solid and must be routed through valves and lines and other suchequipment. Considerable diiculty has been had in controlling suchoperations on account of the nature of the powdered catalyst. Usuallythe catalyst ilows from the reactor to the regenerator and this flow iscontrolled by slide valves which are large hydraulically controlledvalves. Since these are mechanical operations, these valves aresusceptible to all sorts of mechanical dilculties caused primarily bythe nature of the solids owing through the valves. Sometimes the valves,if they remain open for a long period of operating time, may stick andthus make the whole unit unable to control. At other times the valvesmay be only partially opened and partially closed by the iinely dividedcatalyst 2 ious other difficulties are encountered such as erosion. A

In accordance with the present invention, the diiiiculties of the priorart are eliminated by providing a device for controlling a fluidizedsolid operation in which the mechanical controlling means aresubstantially eliminated.

It is, therefore, one object of the present invention to control acatalytic conversion process in which a fluidized solid catalyst isemployed by controlling the ow of the catalyst in relationship to theiiow of a iiuid.

Another object of the present invention is to control a catalyticcracking operation employing a fiuidized powder as the catalyst inwhichthe flow of the uidized powder is controlled in relalship to the owof a 'uid.

Still another object of the present invention is to eliminatesubstantially mechanical controlling means in a uidized catalyticoperation in which a iinely divided solid is employed as the catalyst.

The objects of the present invention are achieved by controlling theflow of catalyst from the reaction zone or regeneration zone of acatalytic operation independent of mechanical t0ntrolling mechanism bymaintaining a head of catalyst on a vertical conduit leading into atransverse conduit and flowing the catalyst from the vertical conduit asa dense phase into a disperse phase in the transverse conduit andregulating the amount of iinely divided catalyst in the' dispersephasein relationship to the amount of a fluidizing medium employed tomaintain a dense phase intermediate a disperse phase into which thecatalyst is introduced.

Brieiiy then, the present invention involves the maintenance of avertical column of catalyst which is introduced into a second verticalconduit into which the rst vertical column leads, the iiow of catalystfrom the rst vertical column being controlled by regulating the ow of afluidizing gas in a conduit connecting into the vertical column ofcatalyst. In a conduit connecting directly into the vertical column adense phase of catalyst formed. This dense phase is introduced into adisperse phase and the amount of catalyst in the disperse phase may becontrolled by regulating the amount of fluidizing medium employed toform the dense phase of catalyst and to form a pressure head in thesecond vertical conduit by varying the density in this conduit. It willthus be seen that the present invention involves the iiowing of catalystfrom a rst vertical conduit into a second vertical conduit and the whichtend to make the valves inoperable. Varregulation of flow of catalystfrom the first ver tical conduit to the second vertical conduit bregulating the amount of uidizing medium in troduced into anintermediate zone between the first vertical conduit and the secondvertical conduit. In the intermediate zone a dense phase of catalyst isformed and this dense phase is then introduced directly into a dispersephase having a separate supply of fluldizing medium, the qiantity offlnelydivided solids in the disperse phase being controlled byregulating the amount of catalyst particles in the dense phase. Thus, byvarying the percentage of solids in the dense phase, which can be doneby regulating the fIow of uidizing medium, the amount of particlessuspended in the disperse phase may also be regulated. It will bereadily seen that the improvement of the present invention allows thesubstantial elimination of mechanical controlling means in controllingthe flow of uidized solids.

The present invention has greatest application in the so-callediiuidized cracking operation and will be illustrated by reference tosuch operation. However, it is to be understood that the invention isnot limited to any particular operation. It

may be applied to any operation in which large quantities of solids arecirculated through conduits as a uid in suspension in a suspendingmedium. Such other applications of the present invention will includethe synthesis of hydrocarbons and oxygenated organic compounds fromcarbon monoxide and hydrogen in which the catalyst for the process islsuspended in the feed gas as finely divided particles, the manufactureof phthalic anhydride from'naphthalene employing uidized solids as thecatalyst and other processes too numerous to mention here.

In applying the process to the cracking of hydrocarbons employing afinely divided powder auch as silica-alumina and other well knowncracking catalysts, such as magnesium oxide, zirconium oxide, titaniumoxide, and the like, either ln admixture with other materials or alone,temperatures in the reaction zone are usually maintained from about 850to about 1100 F. with a preferred range fromabout 930 to about 985 F. Inthe regeneration zone, conditions are maintained to burn oil thecarbonaceous material and carbon from `the catalyst. These temperatureswill embrace temperatures in the range from about 850 to about 1200 F.Ordinarily, however, a temperature of around 1l00 F. will be employed.Some care must be exercised in the control of the temperature at whichthe regeneration proceeds. If temperatures are not controlled, thesevere temperature conditions might cause destruction of the catalyst. l

The pressures employed in the system will vary with the process to beused. In the fluid catalytic cracking of hydrocarbons, pressures in therange from about 3 pounds to about 50 pounds are usually sufficient witha preferred pressure of about l5 pounds .per square inch. In thesynthesis of hydrocarbons and oxygenated organic compounds from carbonoxides and hydrogen, pressures may vary rather widely and in some.instances may be over 500 pounds per square inch. Usually, however,pressures will be in the range from about 150 to about 500 pounds persquare inch. i

The invention will now be further illustrated by reference to thedrawing in which Figure l shows a preferred mode of practicing theinvention with respect to the fluid catalytic cracking of hydrocarbons;

in accordance with the present invention in which the flow of a finelydivided solid from a vertical conduit to a transverse conduit asillustrated; and

Figure 3 shows another detail of an arrangement in accordance with thepresent invention in which the ow of a finely divided solid from avertical conduit to a transverse conduit ,is illustrated.

Referring now to the drawing and especially to Fig. l, numeral IIdesignates a reaction zone of a fluid catalytic cracking unit in which afinely divided solid, such as silica-alumina, is employed and numeral I2designates a regeneration zone of a fluid catalytic cracking unit.Reaction zone I I is iiuidly connected to regeneration zone I2 by way ofvertical conduit I3 and conduit Il leading into regeneration zone I2.Regeneration zone I2 is fiuidly connected to reaction zone II by conduitI5 leading from the regeneration zone l2 and conduit I6 leading into thereaction zone II, conduits I5 and I6 connecting at an angle. The

reaction zone II Yis provided with an outlet pipe I1 leading to afractionation zone, not shown, and regeneration zone I2 is similarlyprovided with an outlet pipe I8 which connects into an electricalprecipitation apparatus I9. Electrical precipitation apparatus orCottrell precipitator I9 is provided with a line or stack 20 fordischarge of combustion gases and a line 2I for recycling of recoveredfinely divided catalyst particles in the manner that will be described.

In operating the fluid catalytic cracking operation, a flow of finelydivided catalyst is initiated into the system with the catalyst owingfrom the reaction zone Il to the regeneration zone I2. The start-upprocedures for such catalytic cracking operations have been well taughtin the patent literature and since in themselves do not form a part ofmy invention, will not be mentioned further here. Sufce to say that acracking operation has been initiated in the reaction zone II and acombustion operation has been initiated in the regeneration zone I2 withthe catalyst flowing from the zone II to the zone I2 and from the zoneI2 to the zone II. A feed hydrocarbon is introduced into the system byway o1' line 22 in admixture with nely divided catalyst which may beadded as make-up through line 23 controlled by valve 24 to compensatefor losses through stack 20. This admixture flows into conduit I8 whereit meets the hot catalyst from regeneration zone I 2 which causesheating and/ or vaporization of the oil introduced by line 22. Steam toaid in the fiuidization of the catalyst in the hydrocarbon in line I6may be introduced by line 25 which ties into lines I5 and I6 at theangle thereof where the two lines meet. 'I'he mixture of steam,hydrocarbon, and catalyst then flows to the reaction zone II through afunnel shaped member 26 and then upwardly into the zone I I where adense phase of catalyst is maintained. The conditions are such inreaction zone II that a catalytic cracking reaction takes place and thecatalyst and reaction products flow upwardly into a separating means 21which may be a cyclone separator, filter, or any other separating meansto remove the finely divided solid particles of the catalyst from theproduct. The catalyst drops backwardly into the Vreaction zone II whilethe products issue through outlet pipe I1 to a fractionation zone, notshown. The catalyst in the reaction zone Il, by virtue of the largediameter of the vessel in which the reaction zone is maintained, has itsvelocity substantially reduced and thus maintains a rather dense phaseoi' catalyst in hydrocarbon and steam. The catalyst falls back to theouter annulus of the reaction zone and drops down to a stripping zone 28in which a stripping medium, such as steam, may be introduced by meansnot shown to remove strippable hydrocarbon and carbonaceous materialfrom the catalyst prior to its dropping downwardly to the cone shapedportion 29 of -reaction zone II and then into conduit I3. A head ofcatalyst is maintained in conduit I3. This catalyst flows downwardlyinto a cone 30 which increases its velocity by restriction of the iow.At this point the catalyst ilowing therethrough is met by a stream ofair or other oxygencontaining gas or iluidizing medium which isintroduced by line 3| controlled by valve 32. This stream introduced byline 3| controls the rate of catalyst addition into the conduit 33. Itwill thus be seen that by manipulation of valve 32 the flow of catalystfrom conduit I3 to conduit 33 may be regulated. The valve 32 may beautomatically controlled in response to various operating conditions inthe unit. A dense phase is formed in conduit 33 into which conduit I3and line 3| converge. This conduit 33 is concentric with conduit I4 andextends upwardly into the vertical portion of conduit I4 as shown. Itwill thus be seen that the dense phase in conduit I3 is introduced intoa disperse phase in conduit I4, conduit I4 being supplied with anindependent source of uidizing medium which may be air or other freeoxygen-containing gas introduced by line 34 and controlled by valve 35.Thus, in effect, a dense phase is formed in conduit 33 and the densephase in conduit 33 is then introduced into a. disperse phase in conduitI4 with the quantity of catalyst in the disperse phase in conduit I4being regulated by control of air introduced by line 3|. It will benoted also that a quantity of air suflicient to form disperse phase inconduit I4 is introduced by line 34. The larger amount of air for thetransporting of the iluidized catalyst particles from conduit I3 intoconduit I4 to regenerator I2 will be admitted by line 34. However. theamount of air introduced by line 3| will be the sole control of theamount of catalyst owing from the reaction zone II to regenerator I2.

The amount of fluidizing medium injected by valve 32 will be governedbythe height of conduit 33 in the vertical portion of conduit I4 and thedensity of vsuspension necessary to balance the pressure at the terminusof conduit I3. In a commercial size unit in which a pressure in therange from 20 to 35 pounds per square inch gauge is carried on theequivalent of conduit I3, the height of conduit 33 in the verticalportion of conduit I4 and the amount of air or iluidizing mediuminjected by valve 32 will be dependent on the pressure carried in thereactor II. For example, in a. unit charging about 35,000 barrels offeed stock per day in which a pressure of pounds per square inch ismaintained in the reactor, the height of conduit 33 and the amount ofair or iluidizing medium will be adjusted to maintain a pressure head ofabout 25 pounds per square inch in conduit 33 and a pressure in conduitI4 of about l0 pounds per square inch gauge. It will be realized thatlowering the height of conduit 33 in the vertical portion of conduit I4and decreasing the amount of fiuidizing medium introduced by valve 32will effect a corresponding increase in pressure differential. When theamount of fluidizing medium such as air introduced by valve 32 isdecreased, the amount introduced by valve 35 should be increased andvice versa.

The disperse phase inline I4 flows into regenerator I2 where combustionconditions are maintained. The catalyst in a suspension in com bustionproducts ows into a separator 36 which, similar to separator 21, may bea cyclone separator, filter, or other equivalent separating meanswhereby-catalyst in a nely divided form may be separated from gases. Thecatalyst falls backward into the regenerator I2 and thence into afunnel-shaped member 31 which connects into conduit I5 and transportsthe catalyst from the regenerator I2 to the reactor Il.

The combustion products discharge by way of line I8 to an electricalprecipitation apparatus |9 which may be a Cottrell precipitator whereinthe nely divided catalyst particles, which may be carried over in thecombustion products, are substantially separated therefrom. These finelydivided particles drop down through line 2| and are carried back by afluidizing gas introduced by line 31 through line 38 to the regeneratorI2 for reuse in theprocess. The flue gases and combustion products aredischarged by a stack 20.

Referring now to Fig. 2, from a standpipe or a vertical conduit avertical column of iinely divided solid particles, from a source notshown, are introduced into a cone-shaped member 5I which in turndischarges into a conduit 52 which is concentric with a larger conduit53. Conduit 52 is provided with a source of a fluidizing gas which isintroduced by a line 54 from a source not shown and the introductionthereof is controlled by valve 55. A valve 56 controls the introducitionof additional amounts of uidizing gases by way of line 51. In conduit 52a dense phase of finely divided solid particles introduced from conduit50 is maintained by introduction of a uidizing gas by line 54. Inconduit 53 a disperse phase of nely divided solid particles ismaintained by introduction of the dense phase into the disperse phasewhich will be formed in the region indicated by the numeral 58. Thedisperse phase is formed by admixture of the dense phase from conduit 52with the additional quantities of luidizing medium introduced by line51. Prior to the presentinvention it was customary to controlintroduction of finely divided particles from a conduit such as conduit50 by mechanical means such as a slide valve. It will thus be seen thatin accordance with the present invention the slide valve is omitted andsubstituted for by a valve controlling a gaseous medium rather than acolumn of solid particles. It is well known to the art that iiow ofgases and other uids may be easily controlled by valves and -sucharrangements. It will be within the spirit and scope of the presentinvention to cause the opening and closing and the regulation of valvein response to some variation in operating conditions in the unit inwhich the dense phase in conduit 55 is introduced into a disperse phasesuch as in the conduit 53.

Turning now to Figure 3, a standpipe or vertical conduit 60 provides avertical column of nely divided solid particles from a source not shownfrom which the nely divided solids pass into a cone-shaped member 6Iwhich discharges into conduit 62. Conduit 62 is exterior to a largerconduit 63. Conduit 62 is provided with a source of uidizing gas whichis introduced through line 64 from a source not shown and theintroduction of the gas is controlled by valve 65. A valve I5 annees 7 vis used to control the introduction oi' fluldizing gas into conduit 83from conduit 81. A dense phase of finely divided solid particles formedin conduit 62v by the introduction of iluidizing gas from line 64 passesupwardly and is introduced into zone 63 at a point indicated by thenumeral Il. A disperse phase is formed at point 68 by admixture of thedense phase from conduit 62 with additional quantities of fiuidizingmedium introduced through line 61. .It is thus seen that it isnotnecessary to maintain pipe 62 on the intex-lor of and concentric withpipe 63 as shown n in previous illustrations in order to obtain theimproved results from the practice of my invention.

The catalyst or the finely divided particles employed in the practice ofthe present invention will generally have particle diameters in therange from about micron to 100 microns with the major amount in therange from about microns to 80 microns. If too large a quantity oi' thecatalyst have particle diameters in the range from about 0 to 20 micronsin an operation such as a fiuidized catalytic cracking operation asdescribed in connection with Fig. 1, a large quantity of the catalystmay be lost through the stack 20. On the other hand. if a substantialamount of the catalyst has particle diameters in the range from 80 to100 microns, uidization characteristics of the catalyst may be impaired.Therefore, a balance between the nely divided particles of the catalystand the larger particles of the catalyst should be maintained.

While the invention has been described with respect to a fiuidizedcatalytic cracking operation, it is to be emphasized that it has broaderapplication than to controlling such operations. It also has applicationto controlling pressure drop across a conduit by opposing a head oifinely divided particles or other materials being transported with aiiuidizing medium to balance the head of finely divided particles.

The nature and objects of the present invention, having been fullydescribed and illustrated, what I wish to claim as new and useful and tosecure by Letters Patent is:

1. A device adapted for suspending finely divided solid catalyst in acatalytic cracking operation having an enlarged regeneration zone with avertical inlet line connecting into the lower portion thereof and anenlarged reaction zone with a vertical outlet line connected into linlet line, a second conduit arranged within said first conduit andconcentric therewith with a discharge end within the inlet line of saidregeneration zone, a hopper member iiuidly connecting said outlet linewith said second conduit, a first.

inlet pipe line including a valve to control the flow of fluid thereinarranged to discharge into said first conduit and a second inlet pipeline including a valve to control the flow of fluid therein arranged todischarge into the second conduit adjacent the point of connection ofthe hopper member with the second conduit.

2. A device adapted for suspending iinely divided solid catalyst in acatalytic operation having an enlarged regeneration zone with a verticalinlet line connecting into the lower portion thereof and an enlargedreaction zone with a vertical outlet line connected into the lower endthereof, a first conduit including a valve to control the flow of fluidtherein having its discharge end connected to the lower end of saidvertical inlet line, a second conduit smaller than said vertical inletline having its discharge end within and concentric with the verticalinlet line, the discharge end of said second conduit pointing upwardlytoward said regenerator and being above the point of connection of thefirst conduit with said vertical inlet line. end, a hopper memberfiuidly connecting the lower end of said vertical outlet line with theinlet end of said second conduit and a third conduit including a valveto control the flow of fluid therein having its discharge end connectedto said second conduit adjacent the point of connection of the hoppermember with said second conduit.

JEWELL S. PALMER.

REFERENCESV CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 2,399,050 Martin Apr. 23, 19462,428,872 Gunness Oct. 14, 1947 2,437,352 Fragen Mar. 9, 1948 2,457,232Hengstebeck Dec. 28, 1948

1. A DEVICE ADAPTED FOR SUSPENDING FINELY DIVIDED SOLID CATALYST IN ACATALYTIC CRACKING OPERATION HAVING AN ENLARGED REGENERATION ZONE WITH AVERTICAL INLET LINE CONNECTING INTO THE LOWER PORTION THEREOF AND ANENLARGED REACTION ZONE WITH A VERTICAL OUTLET LINE CONNECTED INTO THELOWER END THEREOF, A FIRST CONDUIT OF SUBSTANTIALLY THE SAME DIAMETER ASSAID INLET AND OUTLET LINES CONNECTING SAID OUTLET LINE WITH SAID INLETLINE, A SECOND CONDUIT ARRANGED WITHIN SAID FIRST CONDUIT AND CONCENTRICTHEREWITH WITH A DISCHARGE END WITHIN THE INLET LINE OF SAIDREGENERATION ZONE, A HOPPER MEMBER FLUIDLY CONNECTING SAID OUTLET LINEWITH SAID SECOND CONDUIT, A FIRST INLET PIPE LINE INCLUDING A VALVE TOCONTROL THE FLOW OF FLUID THEREIN ARRANGED TO DISCHARGE INTO SAID FIRSTCONDUIT AND A SECOND INLET PIPE LINE INCLUDING A VALVE TO CONTROL THEFLOW OF FLUID THEREIN ARRANGED TO DISCHARGE INTO THE SECOND CONDUITADJACENT THE POINT OF CONNECTION OF THE HOPPER MEMBER WITH THE SECONDCONDUIT.